In recent years, radiation imaging apparatuses using flat panel detectors (hereinafter abbreviated as FPDs) made of semiconductor materials have come into practical use as image capturing apparatuses used in medical image diagnosis and non-destructive tests using X rays. Such radiation imaging apparatuses are used as digital imaging apparatuses for capturing of still image, such as photography, and recording of movies, such as fluoroscopy, for example, in the medial image diagnosis.
Arbitrary switching of the areas (field-of-view sizes) where the readout by the FPDs is performed is discussed in such a radiation imaging apparatus, as disclosed in Patent Literatures 1 and 2.